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Microclimate wind engineering & architectural aerodynamics
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urban regeneration and large-scale masterplan development is placing increasing emphasis on the quality of external areas in the vicinity of buildings for recreational use with a view to making urban life style more sustainable.
Tel: +44 20 8614 4400 Fax: +44 20 8943 3224 Email: [email protected] Website: www.bmtfm.com
the comfort and safety of users in these spaces is
often an imperative requirement for planning approval
and can be crucial to the commercial success of
large-scale developments. as a result, environmental
impact assessments (eia) and environmental design
development requires designers and developers to
embark on detailed study of external microclimate not
only in the pre-planning stages, but also in the detailed
design stages. to support designers in this process Bmt
Fluid mechanics (Bmt) maintains a highly resourceful
and experienced group of micro-climate and building
physics experts, which have developed a number of in-
house numerical and physical modelling.
wind speeds for environmental design are not generally
specified in building codes. as a result, the specification
of wind speeds for environmental design requires careful
analysis of long-term wind statistics that need to be
purposely acquired for the site.
Bmt has access to global wind record databases,
which provide long-term wind statistics. By application
of sophisticated industry-standard wind models of the
atmospheric boundary layer, site-specific wind climate
models are generated for each development.
this process needs to carefully consider the surrounding
terrain of the development. in this way a generic wind
regime is generated for the target site that includes not
only site specific wind statistics but also wind speed and
turbulence distributions incident to the development that
can be simulated in detailed wind modelling studies.
Key services
• wind climate analysis
• Pedestrian wind comfort analysis / environmental impact assessment
• wind comfort analysis for balconies & roof top terraces
• thermal comfort / wind chill assessment
• wind mitigation scheme development
• sunlight / daylight & shadow analysis
• experience-based desk study assessments
• detailed modelling studies
Key BeneFits
• external microclimate control
• interactive wind mitigation scheme development
• interactive design optimisation
Site Wind Climate analySiS Cont
Site Wind Climate analySiS
at an early stage in the design development, experience-
based wind microclimate assessments using desk study
methodology can provide useful guidance to design
development by way of identifying key areas of potential
impact on ground level wind conditions and likely extent
of required wind mitigation schemes. depending on
particular requirements of planning authorities, this level of
wind assessment is often adequate for obtaining outline
planning permission for large-scale development.
increasingly, however, detailed industry-standard wind
modelling studies are required to provide quantification
of spatial extent and severity of ground level impacts in
terms of accepted comfort and safety criteria to support
detailed planning applications.
once comfort and safety classifications have been
derived the wind environment can be easily interpreted in
terms of suitability for intended pedestrian uses, thereby,
allowing the need for inclusion of wind mitigation schemes
in further design development to be gauged.
in the case of high-rise developments, low rise podium
areas, higher level balconies and roof-top terraces / sky
gardens often experience wind conditions which are
unacceptable for intended out-door recreational use and,
therefore, require purposeful development of wind barrier
schemes.
Wind miCroClimate aSSeSSment
Wind Profiles
Wind Frequency Data Weibull Coefficient Analysis Terrain Categorisation
Desk Study
Wind Mitigation Schemes
in addition to wind comfort analysis, in terms of wind
force, Bmt also provides thermal comfort analysis that
considers ambient temperature can be an important
consideration in assessing the suitability of external
microclimate, especially in extremely hot or cold climates.
the assessment of thermal comfort requires application
of 3d dynamic thermal numerical modelling tools such
as tas that can analyse local thermal fluxes due to
convection, solar radiation and advection.
combining these modelling approaches with long
term meteorological data allows annual and seasonal
variation of temperature to be predicted in key areas of
a development. Based on this, an assessment of the
thermal comfort is derived using industry standards for
thermal perception based on stipulated clothing levels.
thermal Comfort analySiS
Sunlight / daylight analySiS
apart from wind, the quality of external microclimate is
also impacted by availability of sunlight and daylight in
key pedestrian spaces, which respectively depend on
direct exposure solar radiation and diffused skylight. Bmt
operates a number of specialist 3d numerical modelling
tools to allow these effects to be reliably quantified
leading to a qualification of the quality of natural lighting in
key spaces and comparison with existing site conditions.
these methods can also be employed where there is
concern over availability of sunlight in internal spaces,
and recommendations for design adjustment made where
appropriate.
accurate determination of the wind regime experienced
by a development requires model-scale boundary layer
wind tunnel modelling. Bmt have developed highly
client-interactive testing methodology, with instantaneous
analysis and interpretation, that allows local mitigation
schemes to be validated for effectiveness and also, in
the case of large scale master plan developments, allows
variation of massing scenarios to be evaluated with full
client participation.
these studies are based on sophisticated multi-channel
instrumentation, which allows simultaneous measurement
of mean as well as gust wind speeds at 140+
assessment locations. smoke visualisation techniques
can also be employed to provide further understanding
of the physical wind flow patterns that may be causing
adverse wind conditions.
the interactive nature of the above approach allows
design and client teams to have maximum real-time
interaction with the solution development process and
makes cost effective use of wind tunnel facility time. with
the availability of web-based video conferencing tools and
high-resolution video monitoring equipment integrated
into the wind tunnel test section, remote interaction with
the test programme is easily facilitated.
Tel: +44 20 8614 4400 Fax: +44 20 8943 3224 Email: [email protected] Website: www.bmtfm.com
Wind miCroClimate aSSeSSment Cont
SuitabilityOutdoor RecreationAccess (Ingress/Egress)Access (Thoroughfare)
MitigationNot RequiredBeneficialRequired
43756 Brent Cross, Cricklewood Drawing No: Prep : S StandfussStatus :
Proposed Development
Worst Seasonal Comfort and Safety Ratings Final 43756/WE/6 Date : 02 Apr 2007
Comfort RatingsLong Periods of Standing/SittingShort Periods of Standing/Sitting
Uncomfortable for All Uses
Strolling / Window ShoppingFast / Business Walking
Safety RatingsSafe for All UsersUnsuitable for General PublicUnsuitable for Able Bodied
North [0°]
West[270°]
PrevailingSector
East[90°]
South [180°]
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Clitterhouse Playing Fields(Phase 2)
Clitterhouse Pla(Phase 1)
Claremont Park
Eastern Park
School Square
Market Square
Station Square
Tower Square
NorthernNature Park
Office District Square
Wind Comfort & Safety ClassificationRoof Terrace Wind Comfort Analysis
TAS Thermal Model
Sunlight Analysis
Temperature Variation Temperature Variation
Wind Tunnel Model for Masterplan Studies
For further information contact: Tel: +44 20 8614 4400 Fax: +44 20 8943 3224Email: [email protected] Website: www.bmtfm.com
BMT Fluid Mechanics Limited, 67 Stanton Avenue, Teddington, Middlesex, TW11 0JY, UK
